1. Field of the Invention
This invention relates generally to the field of electronic surveillance techniques, and more particularly, to techniques for surveillance of the web traffic of an individual (hereafter “user”), such as email and web pages accessed by the user, pursuant to a duly authorized wiretap.
2. Description of Related Art
On Oct. 25, 1994, the United States government enacted the Communications Assistance for Law Enforcement Act (CALEA) to make clear a telecommunications carrier's duty to cooperate in the interception of communications for law enforcement purposes. CALEA requires telecommunications service providers (e.g., telephone companies, etc.) to make available both call content (voice signals) and call data (digits dialed, length of call, etc.) to requesting law enforcement agencies in response to a valid court order.
With the growth of the Internet and related technology, voice traffic is now often carried from point to point over a packet-switched communication path rather than over a circuit-switched communication path. In this arrangement, a voice signal may be digitized and encoded and the resulting bit stream then divided into a sequence of payload blocks. A header is added to each payload block, thereby establishing a packet. Each packet is then routed independently to a destination address in the packet header. At the destination address, the packets are then assembled, and the payload is extracted, decoded and converted back into the underlying voice signal.
Some service providers have provided law enforcement with the ability to facilitate wiretapping of packet-based voice traffic. U.S. patent application Ser. No. 09/793,136, currently pending, assigned to the assignee of the present invention, is directed to wiretapping of voice traffic passing over a packet-switched network. The content of the '136 patent application is incorporated by reference herein.
Techniques currently exist for wiretapping voice calls. In a traditional circuit-switched telephone network, for example, a wiretap can be readily implemented by identifying a specific telephone line or channel (e.g., TDM (time divisional multiplexed) time slot, for instance), intercepting the electrical signal carried along that line, and communicating those signals to a surveillance equipment operator. In response to a proper court order, search warrant or wiretap order, a telecommunications service provider may thereby be required to provide law enforcement officials with real-time access to voice calls.
In the wake of the Sep. 11, 2001 terrorist attacks on the United States, the surveillance of individuals suspected of representing a threat to domestic peace and security has been extended to surveillance of the Internet activity of such persons. For example, if an individual under surveillance is seen to be exchanging emails with known or suspected terrorists regarding their funding of activities or potential targets, or if the individual is seen to be accessing web pages describing how to build biological weapons, that information would be of obvious benefits to law enforcement. The information could conceivably prevent a terrorist attack and thus save many innocent lives.
The problem of surveillance of packet traffic on the Internet becomes somewhat more complicated when the user under surveillance is using wireless communication devices, such as a personal digital assistant or cellular phone, in order to access a network such as the Internet. In a wireless situation, the user and their communications device is mobile, such that the attachment point of the user to the Internet can change over time. Moreover, encryption is performed in the transmission path between a mobile access gateway and the user, rendering surveillance of such traffic and in particular access to the underlying content, more difficult.
The present invention overcomes these problems and provides methods and apparatus for providing packet traffic surveillance for web or other network communications of a person under surveillance. The invention is particularly suited for use in providing surveillance of a user that is using wireless technology for exchanging data (email, web page requests, etc.) with a content server on the network.